**6. Conclusion**

This chapter has described three famous ice caves in China, i.e., Ningwu ice cave, Zibaishan ice cave, and Wudalianchi ice cave. We reviewed quantitative analysis of the formation and preservation mechanism of an ice deposit in Ningwu ice cave, a quasi-static ice cave. The systematic FEM computing leads to the conclusion below: the air natural convection in winter is the crucial controlling factor for forming and sustaining the ice deposit in the cave and can cool the ice cave efficiently. Heat transfer by conduction in spring, summer, and autumn is very limited to warm up the cave. Water-ice phase change plays an important role in summer and can prevent melting of ice. We proposed that Ningwu ice cave and Zibaishan ice cave may be a self-regulating system, respectively, controlled by air natural convection between inside and outside of the ice caves. We expect that no airtight door will be fixed at each ice cave entrance and few people enter the ice cave before comprehensive and detailed studies, avoiding further affecting its natural conditions.
